chore: code review cleanup + bump v0.8.4

- Remove _get_client_for_output() compat shim (replaced by direct _get_client calls)
- Remove unused inspect import
- Fix redundant branch in constants.get_accept_language()
- Add TWITTER_BROWSER docs to README (en + zh)
- Update all test monkeypatch signatures
- Bump version to 0.8.4

README.md

@@ -182,6 +182,12 @@ Browser extraction is recommended — it forwards ALL Twitter cookies (not just
 TWITTER_CHROME_PROFILE="Profile 2" twitter feed
 ```
 
+**Browser priority:** If you have multiple browsers, set `TWITTER_BROWSER` to try a specific browser first:
+
+```bash
+TWITTER_BROWSER=chrome twitter feed    # Supported: arc, chrome, edge, firefox, brave
+```
+
 After loading cookies, the CLI performs lightweight verification. Commands that require account access fail fast on clear auth errors (`401/403`).
 
 ### Proxy Support
@@ -491,6 +497,12 @@ twitter follow elonmusk --json
 TWITTER_CHROME_PROFILE="Profile 2" twitter feed
 ```
 
+**浏览器优先级**：如果有多个浏览器，可通过 `TWITTER_BROWSER` 指定优先尝试的浏览器：
+
+```bash
+TWITTER_BROWSER=chrome twitter feed    # 支持: arc, chrome, edge, firefox, brave
+```
+
 ### 代理支持
 
 设置 `TWITTER_PROXY` 环境变量即可：